Evaluation of Correlations for Natural Convection Cooling of Electronic Equipment

Abstract

For complicated physical arrangements, thermal design information historically has been obtained from experimentation. By interpreting experimental data in the form of nondimensional parameters, results can be applied to situations phenomenologically similar to, but physically different from, experimental conditions. Empirically derived natural convection correlations extracted from the scientific literature are compared with nondimensionalized data obtained from physical models of uniformly heated electronic circuit cards vertically mounted in a frame. Tlie majority of data points were clustered in the modified channel Rayleigh number (Ra“) region of 15 to 100, where densely populated, narrow channeled, and intensely powered circuit card applications occur. The universal correlations of Wirtz and Stutzman [4] and Bar-Cohen and Rohsenow [5] compared quite well with experimental data collected from electronic equipment being developed at AT&T Bell Laboratories and are recommended for 10<0Ra “< 1000. For Ra...